Pilot-directing instrument and bomb-dropping sight for aircraft



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A. H. BOETTCHER PILOT DIRECTING INSTRUMENT AND BOMB DROPPING SIGHT FOR AIRCRAFT LSEQWS Filed March 11 1918 2 Sheets-Shem. '1

@m'. 7, 19%.. 1,510,975 A. H. BOETTCHER PILOT DIRECTING INSTRUMENT AND BOMB DROPPING SIGHT FOR AIRCRAFT Filed March 11. 1918 2 Sheets-Sheet 2 I X 200d 10 f I6 4 A2 /4 Patent Oct. 7, 1924.

ARTHUR H. BOETTGHEB, OF CHICAGO, ILLINOIS.

PILOT-DIRECTING INSTRUMENT AND BOMB-DROPPING SIG-HT FOR AIRCRAFT.

Application filed March 11, 1918. Serial No. 221,837.

To all whom it may concern:

Be it own that I, ARTHUR H. BoET'r- CHER, a itizen of the United States, residing at Chicago, Illinois, have invented new and useful Improvements in Pi1ot-Directing Instruments and Bomb-Dropping Sights for Aircraft, of which the following is a specification.

This invention relates to a pilot directing instrument and bomb dropping sight adapt-.

ed to be carried by aircraft, and contemplates an arrangement whereby an observer at the nose of the machine may convey information to the pilot, 'whose view of an.

objective or target may be more or less obstructed, in order to enable the pilot more efficiently to maneuver the airplane accurately toward the objective and in bomb dropping toward the target for securing a hit on the release of thebomb.

The invention lies primarily in the pilot directing means which, per se, is .useful in any case where accurate direction of flight toward an objective, particularly an objective below, as on the earth, and if need be over such objective, is required, as in bomb dropping, aerial photography, pursuit and navigation, as will be evident to those skilled in the art as this description proceeds; but the use which gave rise to its conception is that in connection with bomb dropping, in which the direction of flight is a fundamental factor, and consequently the invention goes beyond the pilot directing means, per se, and provides a bomb dropping sight in which the pilot directing means forms an inherent part and in which. in addition, certain improvementsin bomb sights, specifically, are contemplated. This specification, therefore, dealing with the problems of bomb dropping and describing a novel bomb sight in detail, sets forth the pilot directing means in a most exacting use.

In order that a clearer perception of the present invention may be had, it may be stated that in dropping bombs from airplanes it is necessary for the pilot to steer his craft into proper position, relatively to the target, amply in advance of the time of dropping, so that the initial velocity of the bomb may lie accurately in the right direction. The pilot should also preferably be advised as to the time of dropping, having various expedients have been devised adapt ed to be actuatedjb the observer who is in a position to View t e sea to assist the pilot in steering the craft into position. The best means thus far devised for this purpose, so far as known, comprises a series of three to five incandescent lights stationed. before the eyes of the pilot and controlled by a corresponding number of electively operated switch buttons at the hand of the observer who, by actuating these buttons communicates to the pilot directions to steer more to the left or more to the right, still more to the left or still more to the right as the case may be. This method of communication like the hand waving, signals which are also used is im ractical and unsatisfactory, the chief di culty being in the fact that it isinore or less haphazard and indefinite, and the length of time to convey the intelligence is so great that it is frequently too late to use the information when the pilot receives it.

So far as the means for determining the line of sight for range is concerned, it may be made more or less elaborate according to see the target, may steer his craft effectivelyunder the direction of the observer,

who is able to see it.

To enable others sln'lled in the art so fully to "comprehend the underlying-features of the invention that they may embody the same into the numerous modifications in structure and relation contemplated by this invention, drawings depicting a preferred form have been annexed as a part of this disclosure, and in such drawings, like characters of reference denote corresponding.

vide a sighting means such" as a tube or bar 6 mounted at 8 for universal movement on a suitable standard 7 at the forward partof the machine, which tube is to be kept by the observer directed at all times upon a discovered target. The pilot is kept advised of the movement of this tube or bar, and is thus enabled to' steer his craft into position. With the use of theinformation thus transmitted to him by the observer, the machine may be readil directed so as to get on the line of the target and finally to assume a proper position relative to the target, at which instant the bomb is dropped by the act of either the observer or the pilot, preferably the former.

The means devisedfor keeping the pilot informed as to the position of the sight tube or bar thus trained upon the target includes an indicating means such as a semaphore ball 10 carried by the tube 6 and a cross-wire frame 11 mounted upon the machine in front of the pilot, through which the pilot can sight the semaphore ball. As shown more clearly in Fig. 1 of the draw ing, the pilot is seated in his cabin while the observer sits or stands in the cockpit in the nose of the machine. The support 7 is directly in-front of the observers cockpit, on the center line of the machine and carries a second rod 12 at right angles thereto. This second rod is adjustable vertically upon the rod 7 and is also adjustable horizontally in a calibrated clamp 13. At the fore end of the rod 12 is a ring holding a disc of tinted glass 14, preferably orange, in order/ to rovide a distinguishing sighting point. Tie joint 8 determines one of the points of theline of sight and the center of the ring 14: is the other determining point,

the effective line of sight being indicated in the drawing by a dotted line 15. The vertically disposed rod 7 is calibrated accord ing to the altitude, and the horizontally disposed rod 12 is calibrated according to the various speeds, (see Fig. 4) and it will therefore be clear that the ring '14: may be adjusted vertically and horizontally according to the altitude and speed to determine the proper range angle of the line of sight.

It has already been stated that the tube is universally mounted, and .it will be clear that this tubemay be brought intoposition with 1ts axis co-incident with the cf fective line of sight, at which time the tinted glass of the ring will lie in front of the tube.

The tube 6 carries a rearward extension, or arm 16, having at the end thereof the semaphore ball or other indicating means 10, so disposedas to be in line with the center line of thetube- The arm 10 carrying this ball is preferably bent'so that the observer zhay position his head, with his eye at the rear end of the tube.

Mounted upon the top of the fuselage or body, directly in front of the pilots position, is the frame 11 of. more or less rectangular shape in which are mounted vertical and horizontal cross-hairs 17 and 18, the horizontal wire 17 being mounted at 20 for vertical adjustment for use in a single point sight. Variations in the physical height of the pilotwill cause certain inaccuracies to enter in. This fact may be overcome by varying the height of the seat of the pilot or by adjusting the wire 17. In other words, the pilots eye should have a relatively fixed angular relationwith respect to the cross-hairs at all times. The tube 6 is preferably provided with an operating handle 21 so that it can be conveniently maneuvered.

While it will be possible to set the calibrated sight while in flight, it is probable that the best plan is to set the sight for normal speed and altitude before going up. Whenever it is set, the cross-wire 17 will also be setas to height so that when the tube 6 is in efi'ective sighting position the intersection of the cross-hairs will be in line with the semaphore ball as seen by the pilot. a

It is also possible to provide compensa tion for up and down wind by having calibrations'22 on the clamping block 13 in which the horizontal rod 12 is mounted, with which the calibrations on this rod may be coordinated, the idea being to use; the zero mark on the block for no wind, another mark for a head wind, and another mark for a rear wind, the marks being further aug-' mentedjf desired by -marks for different velocities.

As shown in detail View in F ig.'4l, the calibrations on the vertical rod 7 are for altitude. For the purpose of illustration, three altitudes: 500, 1,000 and 2,000 feet, are shown. These calibrations can be determined mathematically, the distance from the origin to the points being proportionate to the squares of the altitudes which they represent, if it is assumed that the trajectory is a true parabola, but as a matter of fact it is not atrue parabola, and the calibrations had better be determined by tests. The calibrations on the horizontal rod 12 are for speed, and thedistances between the points are directly proportional to the Values which lStD calibrations on the block are for coordination with the calibrations on the horizontal rod. If the plane is going,down wind, then one of the right hand arrows is selected according to an approximation of its velocity, and if the plane is going up wind, then one of the left hand arrows is selected approximate to its velocity.

In operation it is intended that when the observer spots a target he will wave his arm, or otherwise signal to the pilot, to secure his attention upon the semaphore ball 10, and from that moment on it becomes the observers duty to keep the sighting tube 6 trained upon the target at all times. Depending upon the position in which the pilot finds the semaphore ball in his sight field, he will steer his craft to bring the ball first to the vertical cross-wire and then up the vertical cross-wire to the horizontal crosswire. It will be clear that with the sight tube always trained upon the target the ball will occupy the same relative position in the pilots sighting field as the real target occupies relative to the machine in the real field, it being assumed, of course, that the machine is level both athwartships and fore and aft, or that proper allowance is made by the pilot for tilt and that drift is avoided or allowed for. Whether or not the craft is drifting may be determined by sighting down through the tube 6 along the member .12 upon any object upon the earth. When the object moves (relatively) parallel to the member 12, which is normallyparallel to the keel as shown, there is no drift, the member 12 lying parallel to the actual line of flight of the aircraft over the earth. In the pliots sighting field, the semaphore ball will occupy a position on the side of the vertical sight-wire opposite to that of the target. This is immaterial, but if desired it may be overcome, as for example my the modification shown in Fig. 5 hereinafter described.

Suppose, as indicated in Fig. 2, the pilot sights the semaphore ball 10 in the position there indicated, he will steer his craft towards the left, which action, as the observer keeps the sighting tube trained on the target, brings the ball over towards the vertical cross-wlre. It will be clear how at every instant the pilot is kept advised as he is approachin the line of the target and when the ball nally reaches, the vertical cross-wire, he knows that he has his target dead ahead. He then continues in that direction, and as the observer still follows the target with his sighting tube, the ball will rise along the vertical cross-wire 18 until the horizontal cross-wire 17 is reached,

at which instant the sighting tube will have assumed the effective lineof sight, whereupon the observer or pilot will drop the bomb. The pilot is thus kept advised of the approach of the dropping point, so that he may flatten out and get ready to drop the bomb at the desired instant.

In the modification shown in Fig. 5, the tube or bar 6 is provided with a semaphore ball 10 carried by a rod 16 mounted upon the tube 6, but at right angles thereto, the idea being to keep the semaphore ball 10 on the same side of the target instead of the reverse side, as in the former sketch, as viewed by the pilot, and to bring the ball down in to the sight field rather than up as the craft approaches the target. I

This invention is believed fully to solve the problem herein outlined in a highly efficient manner and accomplish, among others, all of the objects herein set forth.

Without further analysis, the foregoing will so fully reveal the gist of this invention that others can by applying current knowledge readily adapt it for various applications without omitting certain features that, H

from the standpoint of the prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention, and therefore such adaptations should and are intended to be comprehended within the meaning and range of equivalency of the following claims.'

I claim as my invention:

1. In combination with an aircraft body having an observers position and a pilots position, a sighting member at the observers position disposed in the direction of flight of the aircraft, a pivoted sighting member movably mounted at the observers position, and indicating means visible to the pilot showing the movement of said sighting member relative to said first-named sighting member.

, 2. In combination with an aircraft body having a pilots position and an observers position, a sighting member at the observers position disposed in the direction of ill ht of the aircraft, a movable sighting mem er at the observers position, and an indicating device visible from the pilots position, the

location of said second sighting member relative to said first sighting member being a factor in the location of said indicating device.

'3. In combination with an aircraft body being determined by the location of said sighting member.

4. In combination with an aircraft body having an observers cockpit at the bow thereof and a pilots cabin to the rear of said cockpit, a sighting member mounted for universal movement on the bow of said body, and means visible from said cabin for indicating the position of said sighting member.

5. In combination with an aircraft body having an observers cockpit at the forward end thereof and a pilots position to the rear of said cockpit, a sighting member mounted for universal movement at the observers cockpit, a visual field at the. pilots position. and indicating means movable with said sighting member and visible to the pilot in said field.

6. In combination with an aircraft body end thereof and a pilots position to the rear of said cockpit, a sighting member mounted for universal movement at the observers cockpit, and indicating means visible from the pilots position, said indicating means being located according to the location of said sighting member and moved by the movement of said sighting member.

7. In combination with an aircraft body having an observers cockpit at the forward end thereof and a pilots position to the rear of said cockpit, a sighting member mounted for movement in azimuth at the observers cockpit, a second sighting member at the observers cockpit disposed in the direction of flight of the aircraft, a visual field at the pilots position, and indicating means m vable according to the movement of the firstnamed sighting member and visible to the pilot in said field.

8. In combination, two members adjustable relatively to each other and determining a sighting line, a sighting member movably mounted on one of said members and having line determining means, and indicating means the position of which is determined by the position of said sighting member, said sighting member being capable of as' suming a position with its line determining means coincident with said sighting line.

9. In combination, two members adjustable relatively to each other and determining a sighting line, a sighting member movably mounted on one of said members and having line determining means, and means connected to said sighting member for indicating the position of said member to a distant pointfsaid sighting member being capable of assuming a position with its line determining means coincident with said sighting line.

10. In combination, two members adjustable relatively to each other and determining a line of sight, a sighting member movably mounted on one of said members and having line determining means, said sighting member being capable of assuming a position with its line determining means tgoincr dent with said sighting line, and means connected to said sighting member indicating ,means, and indicating means connected to said sighting member, the position of said indicating means being determined by the position of said sighting member, said sighting member being capable of assuming a position with its line determining means coincident with said sighting line.

. 12. In combination, two members adjustable relatively to each other and determining a sighting line, a sighting member universally pivoted on one of said members,

and indicating means, the position of which is determined by the position of said sighting member, said sighting member being capable of assuming a position with its line determining means coincident with said sighting line.

13. In combination with an aircraft body having an o bservers position, and a pilots position to the rear of the observers position, a sighting member having line determining means mounted for universal movement at the observers position, an indicator field visible from the pilots position, a pair of members having parts associated with said sighting member and adjustable relatively to each other and determining a sighting line, said sighting member being capable of assuming a position with its line determining means coincident with said sighting line, and means in said field for indicating when said sighting line and said line determining means are coincident.

14. In combination with an aircraft body having an observers position and a pilots position to the rear of the observers position, a sighting member having line determining means mounted for universal movement at the observers position, an indicator field visible from the pilots position, indicating means movable with said sighting member and visible in said field, a pair of members associated with said sighting memher and adjustable relatively to each other and determining a sighting line, said sighting member being capable of assuming the position with its line determining means coincident with said sighting line, and cross wires in said field.

15. In combination with an aircraft body having an observers position and a pilots position to the rear of the observers position, a sighting'member having line determining means mounted for universal movement at the observers position, an indicator field visible from the pilots position, indicating means moving with said sighting member and visible in said field, a pair of members associated with said sighting member and adjustable relativel to each other and determining a sighting ine, said sighting member bein capable of assuming a position with its line determining means coincident with said sightin line, and adjustable cross wires in said fie d.

16. In a bomb dropping sight, a Vertical member calibrated for altitudes, a horizontal member calibrated for speed, the relative positions of said members determining a sighting line, and a wind scale for adding to or subtracting from the calibrations on said horizontal member.

17. The combination, with an aircraft body having an observers position and a pilots position, of a sighting member universally movable at the observers position and means visible to the pilot indicating any divergence lbetween the vertical plane of the sighting member and the vertical plane of the axis of said body.

18. In combination with an aircraft body means visible to the pilot indicating divergence between the vertical plane of the sighting member and the vertical plane of the line of flight of the aircraft.

19. In combination with an aircraft body having an o'bservers position and a pilots position, of a sighting member movable in azimuth at the observers position, a sighting member set in the direction of flight of the air craft and means visible to the pilot indicating any divergence between the vertical planes of said members.

20. In combination with an aircraft body having an observers position and pilots position, of a sighting member movably mounted at the observers position, a sighting member set in the direction of flight of the air craft, and means visible to the pilot indicating existing divergence between said members.

Signed at Washington, D. (3., this 9th day of January, 1918.

ARTHUR H. BOETTCHER. 

